There has been a requirements for manufacturers to ship electronic bay products with all the circuit packs installed in their associated shelf units or sub-racks. However, it was found that if the circuit packs were fully inserted into the backplane connectors of the shelf units, the vibration which occurs during shipping and transportation caused gold plating on the backplane pins to be fretted or eroded. While the loss of gold on the pins does not degrade performance immediately, it will result in a significant reduction of signal integrity life expectancy. Furthermore, due to the size and weight of the circuit packs, additional support would be required.
Traditionally, circuit packs have been shipped by the manufacturer to customers in custom-designed cardboard containers lined with shock absorbing foam. Substantial costs are involved in material, storage, labour and transportation at both the manufacturing and the customer ends of the procedure with respect to such containers. Therefore, while bay products have been shipped with packs installed into the backplane connectors this form of shipping can expose the manufacturer to long term reliability problems.
Other known solutions to shipping with packs in place have been to employ various pieces of foam material to space the packs away from the backplane. These techniques were not very reliable and could result in having small pieces of the foam contaminating the electronics. Additionally, these solutions did not give the packs the added structural support required for the high vibration and shock forces that would be encountered during surface transportation, especially with respect to larger, heavier products.
Two examples of conventional shipping arrangements may be seen in U.S. Pat. No. 3,973,720 of Aug. 10, 1976 and U.S. Pat. No. 4,072,230 of Feb. 7, 1978.
U.S. Pat. No. 3,973,720 Schmid shows a conventional form of protective cushioning pad for shipping articles that require substantial protection against damage by abrasions, shocks and the like. This specification discloses a protective pad that is formed from a single piece of substantially flat resilient material that is formed into at least two discrete sections, each of which is foldable with respect to another section to form a protective envelope for such articles as electronic instruments and the like. The product incorporates protective cushioning pads and includes fold retention means formed from elongated metallic strips which are sufficiently malleable to permit consecutive folding and unfolding of the container.
U.S. Pat. No. 4,072,230 Mulligan discloses a support assembly for positively gripping relatively large units of electronic equipment in order to minimize damage thereto during shipping. It consists essentially of a normally horizontal base assembly with a pair of upstanding end braces that are rigidly secured to the base assembly at opposite ends thereof. A frame or panel having the electronic equipment rests on the base assembly between the end braces each of which includes a pair of vertical clamping members which are movable towards or away from one another for clamping engagement with an end of the equipment frame. Each end brace also includes normally horizontal clamping members which are movable towards or away from the base member for clamping engagement with another part of the frame such as an edge thereof.